Computers having higher performance than conventional so-called Neumann computers are expected to be provided by utilizing neural networks modeled on biological neural networks, and research and development on neural networks have been actively conducted (e.g., Non-patent Document 1).
In a neural network, units which imitate neurons are connected to each other through synapses. By changing the connection strength by learning, pattern recognition, associative storage, or the like can be performed at high speed to a variety of input patterns.
The following method is effective for pattern recognition: utilizing units which imitate a hierarchical perceptron neural network, after patterns of a mobile unit to be an object are learned as teacher data, image data is given as input data so that the coincidence of the teacher data and the input data is determined, so that whether or not the mobile unit is included is extracted. The hierarchical perceptron neural network includes a neuron circuit that is a unit which imitates neurons and a synapse circuit that is a unit which imitates synapses.
A synapse circuit needs to have a function of storing a connection strength between neuron circuits, a function of multiplying an output of the neuron circuits by the connection strength, and a function of adding the results of the multiplication. Thus, the synapse circuit needs to have a memory for storing the connection strength, a multiplier circuit which has a multiplication function, and an adder circuit which has an addition function.
As a screen of a television (TV) becomes larger, it is desired to be able to watch a high-definition image. For this reason, ultra-high definition TV (UHDTV, 4K, 8K) broadcast has been increasingly put into practical use. Japan, which has promoted UHDTV broadcast, started 4K broadcast services utilizing a communication satellite (CS) and an optical line in 2015. The test broadcast of UHDTV (4K and 8K) by a broadcast satellite (BS) will start in the future. Therefore, various electronic devices which correspond to 8K broadcast are developed (see Non-Patent Document 2). In practical 8K broadcasts, 4K broadcasts and 2K broadcasts (full-high vision broadcast) will be also employed.
Imaging elements are provided in a wide variety of electronic devices such as digital cameras or mobile phones. As described above, UHDTV broadcast has been put into practical use, and accordingly, in recent years, the number of pixels in imaging elements has been increased. In recent years, the number of pixels in imaging elements has been increased; consequently, the amount of data obtained by imaging also has been increased. Therefore, higher speed of reading or transfer of data has been required. A technique in which image data is compressed in order to deal with the increase in volume of image data in accordance with the increase in number of pixels in imaging elements has been known. Patent Document 1 discloses an imaging element module in which differential data between captured image data of the previous period and captured image data of the present period is calculated in taking a moving image or in continuous shooting and data is compressed.